Porosity in ceramic substrates can be augmented by the use of carbon based pore formers; for example, graphite and starch. Pore formers are used when conventional batching methods fail to generate the level of porosity that is desired for the product application. For cordierite and aluminum titanate honeycomb substrates with a base composition suitable for diesel particulate filters a typical porosity level is about 40%. Pore formers are used to raise the porosity to levels above the base level, typically in a range of 50% to 60%. Variation in materials over time can change the average pore size distribution in honeycomb substrates due to the changing attributes of the constituent batch materials. These changes can be due to differences in chemistries, morphologies, or particle sizes for one or more of the batched ingredients. It can be quite difficult or expensive to reduce this variation to the level where it does not have an impact on the resulting product pore size. Variability in the lot-to-lot porosity of honeycomb substrates, for example, diesel honeycomb filters, over time can lead to coating differences and changing pressure drop performance over time. Reducing the honeycomb variations in porosity over time will result in a more consistently performing product in downstream use. The present disclosure describes a method for controlling pore size distribution in porous ceramic honeycomb substrates through the use of two or more pore forming materials having different particle size distributions.